When Secretary of State Cyrus Vance finished praising the "Sullivan Principles," an agreement that asks American corporations in South Africa to bypass the apartheid laws, their architect, Leon Sullivan, shouted out, "We all understand the secretary has to leave, and so I am in charge."

And what Leon Sullivan, the towering Baptist minister and job-training wizard from Philadelphia, was left in charge of was a room of blue-chip corporate executives. Last night's dinner at the State Department was a sociological feat that even in the late 1970s ranked as a racial breakthrough. The fact that Sullivan assembled the top representatives from 70 firms and got Vance to stop by at one of his most critical times, added credence to Sullivan's reputation as one of the most powerful economic forces in America.

"We are here right now," said Sullivan, in front of the podium in the Benjamin Franklin room, and added, pointing across the room, and we want to be over there. I'm just tightening the screws and becoming more raadical."

In March 1977, Sullivan, the founder of the Opportunities Industrialization Centers, an international group of job-training facilities, announced his principles and the support of 12 corporations. Now 133 have signed the agreement to integrate the eating and rest facilities of their factories and offices in South Africa and to give equal pay. One result of the corporation's pressure on the South Africa labor situation, several speakers said last night, was the recent ruling granting legal recognition to black trade unions.

"Ultimately I think all American companies will join the agreement," said Thomas Murphy, chairman of the board of General Motors. "Anyone who has been in South Africa realizes that you have to change the work place." Other companies represented included American Express, Colgate, IBM, Goodyear and Union Carbide.

During his dinner remarks, Assistant Secretary of State for African Affair's Richard Moose elaborated on Vance's support of the private initiative "South Africa poses a series of problems among the most complicated and critical our nation will face in the next decade . . . perhaps not in the sense of the Mideast or SALT, but up in the top three or four." Saying that the South African society of apartheid had "changed little," Moose added, "There can be no doubt your effort is producing tangible results . . . but you are only at the beginning . . . your effort is a dynamic."

When Sullivan took the floor to give a preacher's report of the program," he executives came in for some slight dressing down. "Do not use the principles as camouflage . . . as some have done . . . 20 percent of you are pulling hard. Fifty percent are just pulling, and the rest are being pulled along." But at the end, when the race was on to National Airport before it closed for the night, Sullivan got nothing but pats on the back from the departing executives.